The Elements of economic geology

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Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part III. Earthy minerals

Collection:: Economics Books

[96 ECONOMIC GEOLOGY that soil investigation is the most fundamental of all forms of agricultural research.” The interpretation of chemical analyses requires allowance for climate, economic position, and biological factors. Climate may be especially important. If, e.g. the rainfall belts trend N. and S. and the rocks E. and W. the variations in rainfall may be the most influential factor (cf. Alway and Rost, Soil Science, i, 1915, p. 406). The most extensive soil surveys have been made in the United States, where by the end of 1912 they covered over 520,000 square miles, or 330,000,000 acres (** Soils of the United States,” U.S. Bur. Agric., 1913). The soils are classified primarily according to texture, into clay, sand, sandy loam, and loam, and divided inte over 1700 soil types based largely on climatic factors. The objects of a soil survey are to show the agricultural resources of a district, to pro- vide a basis for the scientific investigation of soil, to lead to its improvement and most suitable employment, and to enable local agricultural advisers to give cultivators reliable advice. Mosier and Gustafson (Soil Physics and Management 1917, pp. 117-18) conclude, ** If the work cease with the map- ping of the soils, very little of real value is accomplished, as the soil survey is only preliminary to a more complete in- vestigation. If, however, the soils are analysed, field ex- periments carried on, reports published giving the results of the work, and recommendations for improved manage- ment made, the farmer may avail himself of all this infor- mation for improving his soil and his farm management generally.” Soil survey of transported soils has been undervalued owing to their irregularity. But sedentary soils have as sudden variations. Rocks composed of thin bands or lenticles of clay and sandstone give equally patchy soils. Some drift areas have a remarkably uniform soil over hundreds of square miles. Whether the soils are too irregular for a survey to be useful has to be decided independently in each case. The soil mapping of drift areas should not be debarred by a general rule.

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